c. Construction of temporary barrier. Noise barriers shall be made of noise-resistant material sufficient to achieve a Sound Transmission Class (STC) rating of STC 30 or greater, based on sound transmission loss data taken according to ASTM Test Method E90. Such a barrier may provide as much as a 10 dBA insertion loss, provided it is positioned as close as possible to the noise source or to the receptors. To be at all effective, the barrier must be long and tall enough to completely block the line-of-sight between the noise source and the receptors. The gaps between adjacent panels must be filled-in to avoid having noise penetrate directly through the barrier.

d. Noise curtains. Noise curtain material may be mounted or hung over perimeter chain link fences, or draped over small noise sources, to form a flexible nose barrier. The chain link fences can also be attached to the top of jersey bases.

3. Alternative barriers may be utilized in accordance with site-specific conditions. For example, shipping container (Conex) boxes are likely already available to the responsible party. For example, where work site space permits, these container boxes or truck trailers may be positioned along the edge of the work site to form a semi-permanent noise barrier. These containers are typically 8 feet wide by 8 feet tall and can be double-stacked to form a noise barrier 16 feet in height. The gaps between and/or under container boxes shall be filled-in to avoid having noise flanck around or under the container boxes.